The M3 half-track began as a development of the earlier M2 half-track car in 1940. The U.S. sought a versatile vehicle that could transport troops while offering more protection and mobility than trucks. To speed up production, its design relied on commercial components, with major contracts going to Autocar, Diamond T, and White Motor Company. By the war’s end, about 15,000 standard M3s and more than 38,000 variants had been built. The vehicle was 20 feet long, over 7 feet wide, and weighed around 8 tons. Powered by a White 160AX 6-cylinder gasoline engine producing 148 horsepower, it carried a driver and up to 12 infantrymen. Its armor ranged from 6 to 12 millimeters, enough to stop small-arms fire but vulnerable to heavier weapons and shrapnel. The open-topped design drew criticism from crews, but its reliability, ease of production, and adaptability made it indispensable. Squads often added extra racks and storage for supplies, while modifications in 1942 included racks for mines and rear-mounted luggage racks. Armament varied across models. Early M3s mounted a .50-caliber Browning machine gun behind the front seats, while the M3A1 introduced an armored pulpit mount above the passenger seat, plus mounts for .30-caliber machine guns along the passenger compartment. These features improved its effectiveness as both a transport and a support vehicle in combat zones. The M3 proved highly adaptable. Dozens of variants were created, ranging from self-propelled artillery and anti-aircraft platforms to specialized command and reconnaissance vehicles. During World War II, they were used by the U.S. Army and Marines, as well as supplied to British Commonwealth forces and the Soviet Union. The vehicle served in every major theater of the war, from North Africa to Europe to the Pacific. After 1945, the M3 half-track remained in service across the world. It appeared in conflicts of the Cold War in the Middle East, Africa, Asia, and South America. Despite its vulnerabilities, it continued to serve both states and non-state forces, remaining in use into the mid-1990s. Its longevity came from its rugged design and the sheer numbers produced, ensuring its presence on battlefields for more than five decades.